.\" Copyright (c) 2002 Tim J. Robbins
.\" All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\"    notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\"    notice, this list of conditions and the following disclaimer in the
.\"    documentation and/or other materials provided with the distribution.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
.\" $FreeBSD: src/lib/libc/locale/wcwidth.3,v 1.6 2004/08/17 04:56:03 trhodes Exp $
.\"
.Dd August 17, 2004
.Dt WCWIDTH 3
.Os
.Sh NAME
.Nm wcwidth ,
.Nm wcwidth_l
.Nd "number of column positions of a wide-character code"
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In wchar.h
.Ft int
.Fo wcwidth
.Fa "wchar_t wc"
.Fc
.In wchar.h
.In xlocale.h
.Ft int
.Fo wcwidth_l
.Fa "wchar_t wc"
.Fa "locale_t loc"
.Fc
.Sh DESCRIPTION
The
.Fn wcwidth
function determines the number of column positions required to
display the wide character
.Fa wc .
.Pp
Although the
.Fn wcwidth
function uses the current locale, the
.Fn wcwidth_l
function may be passed a locale directly. See
.Xr xlocale 3
for more information.
.Sh RETURN VALUES
The
.Fn wcwidth
function returns 0 if the
.Fa wc
argument is a null wide character (L'\e0'),
\-1 if
.Fa wc
is not printable;
otherwise, it returns the number of column positions the
character occupies.
.Sh EXAMPLES
This code fragment reads text from standard input and
breaks lines that are more than 20 column positions wide,
similar to the
.Xr fold 1
utility:
.Bd -literal -offset indent
wint_t ch;
int column, w;

column = 0;
while ((ch = getwchar()) != WEOF) {
	w = wcwidth(ch);
	if (w > 0 && column + w >= 20) {
		putwchar(L'\en');
		column = 0;
	}
	putwchar(ch);
	if (ch == L'\en')
		column = 0;
	else if (w > 0)
		column += w;
}
.Ed
.Sh SEE ALSO
.Xr iswprint 3 ,
.Xr wcswidth 3 ,
.Xr xlocale 3
.Sh STANDARDS
The
.Fn wcwidth
function conforms to
.St -p1003.1-2001 .
